- xml:id processing: xml:id [<a href="#XMLID">XMLID</a>] is an ID attribute in an XML

document. Copying an ID attribute from one element to another one is
always wrong behavior. Applications that encounter xml:id attributes
that would need to be copied around by a conforming implementation of
Canonical XML 1.0 hence experience an error condition. Problem could
be caught by implementations of XML Signature that are xml:id aware
always doing duplicate ID checking.

[XMLDSig Issues]

A related problem appears when derferencing the fragment-only
URI-Reference (URI="#some-fragment") of
XML Signature [<a href="#XMLDSIG">XMLDSIG</a>] <ds:Reference>s
in combination with xml:base. In particual It is not
clear whether such a reference is to be dereferenced according to
<a href="http://www.w3.org/TR/xmldsig-core/#sec-ReferenceProcessingModel">
XML Signature Reference Processing Model</a> as node-set-data or octet stream.
This is unclear because XML Signature [<a href="#XMLDSIG">XMLDSIG</a>] is
quiet about (xml:base).